Underwater flash producing system



1959 H. E. EDGERTON 2,872,622

UNDERWATER FLASH PRODUCING SYSTEM Filed June 18, 1954 4 Sheets-Sheet 1 37 39 1092 43 5s 1 Lil Q} 13 115 3 Q )1 l l; j; r

6%.2 INVENTOR.

ATTORNEYS 1959 H. E. EDGERTON 2,872,622

UNDERWATER FLASH PRODUCING SYSTEM Filed June 18, 1954 4 Sheets-Sheet 2 IN VEN TOR. flflx'om 6. 500mm ATTORNEYS Feb. 3, 1959 H. E. EDGERTON 2,872,622

UNDERWATER FLASH PRODUCING SYSTEM Filed June 18. 1954 4 Sheets-Sheet 3 235' U V V 77 231 (11/ 229 33 l 1 2 241 I 2: .L i

2&7 O 1 I N V EN TOR. fl/ZQOLD 5 500mm BYZ. M

ATTORMEYS Feb. 3, 1959 H. E. EDGER'II'ON 2,872,622

UNDERWATER FLASH PRODUCING SYSTEM Filed June 18. 1954 4 Sheets-Sheet 4 Z I 2 23 213 3 33 g0? [42k a i I L 2 7 $61 4, 331 INVENTOR. fl/QROLDf. .'oamro/v BY ATTORNEYS United States PatentO UNDERWATER FLASH KRODUCING SYSTEM Harold E. Edger-ton, Belmont, Mass.

Application June 18, 1954, Serial No. 437,647

9 Claims. (Cl. 315-157) The present invention relates to underwater flash-producing systems and more particularly to systems utilizing electric-discharge devices for producing flash illumination of very short time duration for such purposes as flash-' I for underwater illumination since they do not produce very high peak illumination and they, like the continuous light sources, disturb live underwater objects in view of the substantial time duration of the flashes.

An object of the present invention, accordingly, is to provide a new and improved underwater light-flash-producing system that is not subject to any of these disadvantages and that, to the contrary, may be utilized to photograph animate objects without disturbing them. This result is attained through the use of portable and compact flash-discharge apparatus that may produce flashes of time duration of the order of several thousandths, ten thousandths or hundred thousandths of a second, more or less, which are sufficiently rapid so that animate objects are unaware of the flash, but which are, however, of high enough intensity to permit of exposing a photographic film.

A further object is to provide a new and improved flashproducing system of more general application which may, if desired, be utilized for other purposes in which portahility, ease of operation and operation under inclement weather conditions, or any one of these conditions, may be desired.

An additional object is to provide a new and improved flash-producing electric circuit that is particularly adapted for the above purposes.

Another object is to provide a system of the character described that is particularly suited for the automatic taking of successive photographic exposures.

Other and further objects will be explained hereinafter and will be more particularly pointed out in the appended claims.

The invention will now be described in connection with the accompanying drawings Fig. 1 of which is a perspective view of a flash-photography apparatus constructed in. accordance with a preferred embodiment of the invention, parts being shown broken away to illustrate details of construction;

Fig. 1A is fragmentary section, taken upon the line 1A1A of Fig. 1, looking in the direction of the arrows,

and drawn upon an enlarged scale;

Fig. 2 is a fragmentary perspective view, also upon a larger scale, taken along the line 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a section taken upon the line 3-3 of Fig. 1, looking in the direction of the arrows;

Fig. 4 is a circuit diagram of a preferred electric circuit for operating the flash apparatus of Fig. 1;

Fig. 5 is a perspective view similar to Fig. 1 illustrating a modified use of the apparatus of Fig. 1;

Fig. 6 is a circuit diagram of a synchronizing circuit and apparatus for the system of Fig. 7;

Fig. 7 is a side elevation, shown partly broken away and sectioned, illustrating the use of the present invention in an automatic photography system; and

Fig. 8 is a sectional view of the camera of Fig. 7, viewed from the opposite side.

Referring, first, to Fig. l, a camera housing 1 is shown provided with a hand frame 3 that may permit it to be manipulated by an underwater operator 2. The camera housing 1 may be of any desired conventional watertight construction, embodying, for example, a gasketprovided cover 5 bolted or otherwise hermetically sealed to the housing 1 and provided with a transparent watertight window 7 disposed opposite to the camera lens 4. The shutter mechanism of the camera, not shown, may be controlled by a push button or plunger 9 on one side of the housing 1, shown to the left in Fig. 1, so that inward movement of the plunger 9 will operate the shutter of the camera as is Well known. Projecting upward from the camera housing 1 are a pair of parallel struts 11 that are preferably apertured at a plurality of regions 13 in order to permit the insertion therein of cylindrical weights 15. The weights 15 permit the underwater operator 2 to dive down to desired depths with the apparatus, and to manipulate the same underwater. If more buoyancy is required, some of the weights 15 may be replaced by cork or wood elements and the like. At the upper ends of the struts 11 there is pivotally mounted at 6 a tubular cylindrical housing 17 containing the flashillumination equipment. The housing 17 for the lightflash-producing apparatus may be pivoted about the pivot 6 to any desired angle with respect to thestruts 11 by adjusting a wingnut 19 within a slot 18, Fig. 3. While in Fig. 1, the struts 11 are shown vertically oriented and the housing 17 is mounted substantially horizontally, the housing 17 may be pointed upward or downward, as illustrated in connection with the housing 17 of Fig. 5. In fact, when the equipment is to be stored or transported, the housing 17 may be pivotally collapsed adjacent the struts 11, as shown in the dotted-line position 17 of Fig. 3. At the front of the cylindrical housing 17, corresponding to the window 7 of the camera housing 1, there is provided a transparent hermetically sealed window 21, as of Plexiglas, through which the flash illumination, produced by a flash-lamp 23 mounted in the focal region of a preferably parabolic reflector 25, may pass in order to flash-illuminate the object or scene 10 to be photographed by the camera 1.

By causing the movement of the shutter-operating plunger 9 synchronously to effect the triggering of the flash-lamp 23, the underwater diver 2 may readily obtain flash exposures of underwater life or other underwater objects. This synchronization may be effected, for ex ample, by mounting a contact member 27 upon the shutter plunger 9 within a sealed chamber 29 attached to a side of the housing 1. The contact member 27 may be connected to a conductor 31. A further contact member 33, connected to a further conductor 35, may be disposed within the chamber 29 to become engaged by the contact member 27 when the plunger 9 is pushed inward to open the camera shutter. The conductors 31 and 35 are therefore connected together by the engagement of the contact members 27 and 33 when the operator 2 pushes the shutter-mechanism plunger 9 inward. The conductors 31 and 35 are carried to the housing 17 by an desired gas-at any desired pressure, and having an internal principal anode electrode 37 at one end, an internal principal cathode electrode 39 at the other end, and an external trigger, control or band electrode 41 disposed intermediate the ends of thetube.

The flash tube may, however, be of any other desired type such as is described, for example, in my United States. Letters Patent No. 2,478,901, issued August 16, 1949, or of the type described in Letters Patent 2,492,142, issued December 27, 1949, to Kenneth J. Germeshausen, or of any other type,

embodying any desired shape, configuration, type of electrodes or gases. A'bank of parallel-connected condensers or capacitorsf43, provided with common terminals 45 and '51, is connected by conductors 47, 49 and by conductor 53, respectively, between the cathode 39 and the anode 37 of the flash tube 23. This bank of condensers 43 is preferably mounted near the forward end of the cylindrical housing 17, along the axis of the same, as

shown in Fig. l. The condensers 43 are charged with a relatively high voltage that, as later explained, is preferably, however, low with respect to the voltages customarily utilized in such flash equipment, from two groups of storage batteries 55, 57, preferably of the dry-cell type. The batteries 55, 57 may also be mounted upon a chassis in line with the condensers 43 within the housing 17, though rearward thereof, as illustrated in Fig. l. The lower or terminal of the batteries 57 may be connected by a conductor 61 to a plug connector 63, which,

, when engaged with a cooperative plug connector 65, provides a connection from the conductor 61 to a conductor 67. The conductor 67, in turn, is connected to the conductor 47 andhence to the lower terminal'45 of the bank of condensers 43. The upper or terminal of the batteries 57 is connected by a conductor 69 and the plug connectors 63 and 65 to a further conductor 71. The conductor 71 is connected to one electrode 73 of a switch element "75, preferably of the mercury-switch type.

The mercury switch may be mounted on one side of the L. "batteries 55, Fig. 1A. When the mercury pool 77 of the switch .75 is tilted within the switch 75, electrical contact may be established from the electrode 73 through the pool 77 to the other elecrode 79. The conductor '71 is thus connected to still a further conductor 81 that is preferably grounded or connected to a terminal of the chassis of the apparatus, as shown at 82. The conductor 81 connects to a further plug connector 83 which, when mated with a cooperative plug connector 85, establishes a connection to the lower or terminal of the batteries 55. The terminal of the batteries 55 is connected by still an additional conductor 87 and the plug connectors 85 and 83 through a charging resistor 89 to a conductor 91 that connects by conductor 53 to the upper terminal 51 of the bank of conductors 43.

When the respective plug connectors 63, 65 and 83, 85

, are connected together, and the switch 75 is tilted to es tablish electrical connection between its electrodes 73 and 79, therefore, the bank of condensers 43 becomes charged from the batteries 55 and 57 through the charging resistor 89. The voltage at which the condensers 43 are charged is preferably insufficient to break down the gas within the flash-tube 23, so that the condensers 43 cannot normally discharge through the tube 23 between the anode 37 and the cathode 39 thereof. Such discharge and energization of the flash-tube23, to the contrary, is preferably effected only upon energization of the trigger or control electrode 41. The trigger circuit within the housing 17 for energizing the trigger electrode 41comprises a normally non-conductive ineffective elec Fig. l.

tric-discharge trigger tube 93 of the gaseous-discharge thyratron type, having an anode 95, a cathode 97, an internal control electrode 99 and, as will be later explained, an external trigger electrode 191 which may comprise turns of wire wound about the envelope of the tube 93. Other types of trigger or switch devices may also be used. A further condenser or capacitor 103 is employed, at the appropriate instant, to discharge through the trigger tube 93 when the tube is rendered effective. When a further mercury switch 127, similar to the switch 75, is tilted, as shown in Fig. 1, its electrodes 125 and 129 become connected together by the mercury pool 1'77 and effect the charging of the con denser 193. This charging occurs in the circuit trace able from the upper terminal of condenser 1113, by conductor 165 to resistor 123, through the switch 127, resistor 89 and plug connectors 83 and 85 to the terminal of batteries thence, from the terminal of batteries 55' and conductor 31 to the lower terminal of condenser 103. The upper terminal of the condenser 193 is also connected by conductor 105 to the anode 95 of the trigger tube 93. The lower terminal of the condenser 103 is further connected to the ground or chassis terminal 82, which, in turn, connects with the lower terminal 12 of the primary winding 107 of a trigger transformer 109. The transformer 199 may be mounted within the housing 17, forward of the condensers 43, as shown in The upper terminal 14 of the primary winding 107 is connected to the cathode 97 of the trigger tube 93.

Discharge of the capacitor 1113 takes place through the trigger tube 93 and the primary winding 107 in series. It will be produce a trigger impulse in the primary winding 107 that maybe stepped-up in the secondary winding secondary winding 113 is connected by conductor 20 to the trigger electrode 41 of the flash-tube 23, and the lower terminal of the secondary winding 113 is connected to the lower terminal 12 of the primary winding 107. The discharge of the condenser 1193 through the trigger tube 93 and the primary winding 107, thus, applies a trigger stimulus to the trigger electrode 41 through the secondary winding 113. This trigger stimulus tends partially to break down the gas in the flash-tube 23 and thus permits the condensers 43 to thereupon discharge their voltage between the anode 37 and the cathode 39 of the flash-tube 23, producing an instantaneous flash of light of high intensity. Such light is known to have characteristics that permit of true color photography, which is important underwater.

It remains to explain how'the trigger tube 93 is itself operated to produce the instantaneous flashing of the hash-tube 23. As before explained, the closing of the con tactors 27 and 33, Fig. 2, synchronously with'the opening of the camera shutter, connects together conductors 31 and 35. These conductors 31 and 35 are shown in Fig. 4

:entering the tubular housing 17 of the flash-producing nal 11-9 of a still further condenser 121. This further condenser 121, like the trigger-tube condenser 103, is normally charged from the battery 55. The right-hand terminal of the condenser 121 is connected through a .primary winding 131 of a further transformer 133 to the ground terminal 82 and by the conductor 81 and .plug connectors 83 and to the negative or terminal of the batteries 55. The left-hand terminal 119 of the condenser 121, on the other hand, is connected through a further charging resistor 135 to an intermediate positive terminal 22 of the batteries 55, so that a lesser voltage charges the condenser 121 than the condenser 103. 'When'theconductors 31 and 35 are connected together by the operation of the shutter plunger 9, the lefthand terminal 119 of the; condenser 121becomes connected through the connected conductors 31 and 35 to the ground terminal 82, and thus across the primary winding 131 of the transformer 133. The condenser 121 thus thereupon discharges through the primary winding 131. This discharge produces an impulse in the secondary winding 137 of the transformer 133 that rapidly raises the voltage upon the control electrode 99 of the trigger tube 93 with respect to the terminal 82, rendering the tube 93 conductive and hence effective between its anode 95 and its cathode 97. The condenser 103 thereupon discharges through the thyratron 93 to effect the triggering of a flash in the flash-tube 23, as before described. As the shutter-mechanism plunger 9 is thus operated by the underwater diver 2,to open the shutter mechanism of the camera 1, the flash-tube is synchronously flashed. Release of the shutter-mechanism plunger 9, which may be spring-operated to return to its normal position, renders the trigger circuit adaptable for re-charge to ready the same for a second flash at a subsequent time.

In the event that it is desired, on the other hand, to

' cause the presence of some illumination or other radiation in the water automatically to trigger off the flashtube 23, the trigger tube 93 may be triggered by photocells or similar devices 139, preferably mounted within the reflector 25, as shown in Figs. 4 and 5, to the sides of the flash-tubes 23. The camera shutter would then be normally maintained open. The anodes 141 of a pair of such photocells 139, disposed within the reflector 25, may be connected in parallel to a conductor 143, and thence to the upper terminal of the charging resistor 123. The cathodes 145 of the photocells 139 may be similarly connected in parallel by a conductor 147 through a further resistor 149 to the conductor 67 which, in turn, as before stated, is connected ultimately to the negative or terminal of the batteries 57. The photocells are thus supplied with operating voltage from the batteries 55 and 57 when the mercury switches 127 and 75 are in operative positions, Fig. 1. Any illumination or other radiation falling upon these photocells 139 will cause a variation in the current passed through the resistor 149. Since, however, the upper terminal of this resistor 149 is connected, also, to the external control electrode 101 of the trigger tube 93, this will serve to increase the voltage upon the electrode 101 and thus to render the trigger tube 93 conductive, thereby to trigger the flash-tube 23, as previously explained.

In accordance with the present invention, therefore, either the operator 2 may deliberately flash the apparatus to take a picture, or some radiation phenomenon under water may itself operate the flash mechanism. In this connection, one or more substantially identical flashproducing apparatus may be positioned in the water or carried by another underwater operator 30, as shown at 17 in Fig. 5, to provide side or other supplemental illumination. The flashing of the flash-tube 23 of the flash apparatus 17, by the underwater operator 2, for example, will provide illumination that, falling upon the photocells 139 carried in the second flash-producing apparatus 17, will thereupon trigger the supplemental flash-producing device 17 to produce additional illumination.

It is now in order to explain some of the electrical advantages obtained with the aid of the type of circuit disclosed in connection with the embodiment of Fig. 4. Through the use of the plurality of trigger electrodes 99 and 16.91, of course, flashing may be produced either as a result of internal synchronization from the camera-shutter mechanism, or as a result of external triggering, as from an outside source of radiation. The use of two sets of plug connectors 63, 65 and 83, 85 associated with the respectivebatteries 57 and 55, enables the voltage sources to be easily disconnected in order to isolate the circuit from voltage in the event that repairs are necessary. The mercury or similar position-operated switches 75 and 127 serve at least two important purposes. First, the upper switch 127, if oriented to its inoperative position, Figs. 1A and 4, keeps voltage off the trigger-tube anode 95, so that the trigger circuit cannot possibly operate the flash-tube 23. if the other mercury switch 75 is not employed, the voltage of the upper and lower banks of batteries 55 and 57 might bleed off through the capacitors 43. The introduction of the mercury switch 75, however, prevents such a condition. Shunting the secondary winding 113, of the trigger transformer 1159, moreover, is a spark or air gap that has been found to aid in the starting of the flash in the flash-tube 23. This important feature may be explained as follows. It is desirable in units designed for the purposes described, that the voltage upon the capacitors 43, as before indicated, be relatively low compared with the voltage utilized in more conventional flash-discharge circuits operated in air, say, of the order of four or five hundred volts, more or less. It is, of course, important where electric equipment is being operated near or in the water, that the voltages be maintained relatively low. Normally, the distributed capacitance between the trigger electrode 41 and the cathode 39 of the flash-tube 23 produces, in cooperation with the impedance of the secondary winding 113 of the trigger transformer 109, a relatively low resonant frequency, say, of the order of 20,000 cycles. The spark gap 115 serves to discharge the voltage developed in the said distributed capacitance 'between the trigger electrode 41 and the cathode 39, by breaking down to provide a shunt path thereacross. This shunt path, however, is of low inductance compared with the inductance of the secondary winding 113 of the trigger transformer 169, so that the resonant frequency of the said distributed capacitance together with the inductance of the shunt path produced by the arcing spark gap 115, is very much higher than 20,090 cycles. The resulting very high frequency radiation passes through the envelope of the flash-tube 23 and into the gas thereof and hasbeen found to assist in effecting th ionization of the gas. Through the use of the shunt spark gap 115, the ionizing and flashing of the tube 23 is insured upon the energization of the trigger electrode 41, even though the voltages utiiized may be less than those normally employed in flash-producing equipment.

A further advantage of the circuit of Fig. 4 resides in the Ion impedance synchronizing circuit provided by shorting the conductors 3i and 35. The normally dele terious effects of moisture and salt water are thus obviated with such a triggerdnitiating device. The banks of batteries 55 and 57, moreover, are intermediately connected to the chassis at 82, thus, again, minimizing the problems of operating voltages in dampness and moisture.

Turning, now, to the mechanical advantages of the invention, the cylindrical housing 17 and the described arran gement of the parts therein not only simplifies the packaging of the equipment, but also facilitates rapid repair. It is merely necessary to remove the gasket-mounted Plexiglas or other window 21 frontend cap and to remove the other end plate 151, thereby to slide the apparatus chassis out of the watertight housing 17. The details of construction of the mounting of the window 21 and the end plate 151 may be similar to those illustrated in the embodiment of Fig. 7. The mechanical construction of the system, moreover, provides dynamic balance so that the operator 2 may hold the apparatus in any desired position without tipping. By proper adjustment of the weights or other bars 15, the apparatus may be held level so that,.as the operator steadies it, it has neither a tendency to sink nor to float. The use of an air space within the camera housing 1 and within the casing 17 provides further buoyancy to the apparatus, and the walls of the housings 1 and 17 may be weighted to obtain any desired balance. in general, however, the balance criterion to be achieved is that the average density of the whole apparatus should be substantially the same as that of the water in which it is being used and the dynamic to take a photograph.

paratus is held in a position such that the mercury switches 75 and 127 are in their inefiective positions, as illustrated in Figs. 1A and 4, the operator 2 may swim about with the apparatus without any danger of false operation. This can be achieved by holding the apparatus 1 17 on its side, as illustrated in Fig. 1A, until it is desired Merely by orienting the apparatus into the position shown in Fig. 1 where the mercury switches 75 and 127 are tilted to their operative positions,

the apparatus is immediately readied for and effective for use. External rotation or other orientation of the apparatus, therefore, renders the system either ineffective or efiective for operation without the need for any external Wires, switches and the like, except for the camera-shutter operating mechanism. This mechanism may also be eliminated when photocell triggering is used, as previously explained, or when an automatic operation is effected as later described in connection with the embodiments of Figs. 7 and 8.

An illustration of the details of a practical apparatus of 7 this character follows. First, with regard to the circuit of Fig. 4, the trigger tube 93 may be of the RCA 5823 type with an external electrode comprising it) turns of bare wire. The capacitors 43 may be approximately 525 rnicrofarads each. The voltage to which the capacitors 43 are charged may be about 450 volts, and the batteries 55 and 57 may comprise banks of 9G=volt drycell batteries. For use in the low-impedance type of grounded triggering circuits i i-35, the condenser 121 may havea value of about 0. microfarad and the re sistor 105 may have a value of about 1 megohm. The resistors 39, 123 and ii? ma have respective values of about 125,000 ohms, 190,680 ohms and 10 meg-ohms. The trigger-tube condenser N3 may have a value of about 1 microfarad and the photocells 39 may be of the RCA 934 type. The flash-tube 23 should be ofv the low voltage starting type and may, for example, be a General Electric YET-218 tube. The gap separation in the air gap 115 across the secondary winding of the trigg r transformer 19? is preferably of about from to about of an inch for this particular circuit. In connection with the mechanical details, the casing 17 may have a length of about two feet and a diameter of about six inches. It may be constructed of brass tubing having a wall thick ness of about 0.l inch. T he camera housing 3 may weigh about ten pounds, and the struts ll may be about two feet long.

The present invention is not restricted to use with a human operator 2. It is, indeed, unnecessary that an operator be associated in any way with tbeequiprnent other than to lower the same into the water. In Figs. 7 and 8, therefore, an apparatus is illustrated that embodies a tubular flash-apparatus housing 17 of the type previously discussed in connection with the embodiment of Fig. l, and a camera housing 261. A cable 3 3 suspends the flash-apparatus housing 17 at a downward incline in order to direct the light flashes at a scene it to be covered by the camera. The camera housing may, in this case, also be of tubular cylinder construction having a lens 263 for focusing an underwater object or scene 12 upon a film 205. The camera housing 2 may be suspended from the housing 17 by proper lengths of cables 152 to maintain the camera substantially horizontal when lowering it. The film 295, such as 35-millimeter moving-mo ture film, is shown wound upon a supply reel 2%? and fed therefrom over guides 299 and over a sprocket 211 to take-up reel 213. A conventional gate 215 may be disposed between the lens 2%.?) and the film 2&5 to permit the passage of the film. A motor 217 is mounted on one side of a vertical chassis 223. its shaft 216 extends through to the other side Where it drives take-up and negative side of the battery 235.

'8 217 is operated at periodic intervals otjtime to expose a new portion of the film 295 after each flash of the flashapparatus 17 in order 'to enable the automatic taking of successive flash photographs. This-operation may be more clearly understood by referring to the circuit diagram of 6 where the motor is schematically illustrated at 217. Upon the shaft of the supply reel 2%? there is mounted a cam 225 that is rotated in response to rotation of the shaft 216 of the motor 217. This is schematically illustrated in Fig. 6 by the dotted line connecting the motor 217 and the cam 2-25. It is shown in Fig.

-8 as effected by the pulley belt 221 'The cam is provided with a pair of oppositely disposed contact members 22."! and 2.25. A timing device is used to move the film 2il5 by operating the motor 217 after the production of a dash of light. This timesdelay device 243 may take the form of an armature 249 controlled by a relay coil 245 and re-set by'a time-controlled spring or other return device Z65,'sucl1 as an "Agastat type of mechanism. Two switches 255 and 251 are synchronously opened or closed by the movement of the armature 249. When the armature 249 is displaced to the left, the switch 255 is closed, shorting contacts 259. The right-hand terminal of the motor 217 is then connected by conductors 331 and 2'53 to the chassis or ground at 247. Since the negative side of a motor battery 235 is also grounded at Zol, the right-hand terminal of the motor 217 is connected to the The left-hand motor terminal is permanently connected by conductor 333 to the positive terminal of the battery 235 so that the motor is now energized and starts to rotate the cam 225. The

' cam contact member 227 then connects with the fixed contact member 23?. keeping the motor connected across the battery 235 and thus rotating until these contact members disconnect. in the meantime, the closing of the switch 251 with contacts 257 causes the battery 235 to feed energy to the relay coil 245, returning the armature 249 to the right and opening the switch 255. When the cam contact members 227, 231 have become disconnected, the motor 217 is therefore no longer connected through the switch 255 to ground, and is de-energized. The spring or other time-delay device 265 is then operative to push the armature 249 to the left again, re-starting the cycle. After the film 295 has been advanced to a new position, moreover, the contacting of the further cam contact member 229 with the fixed contact 233 effects the short-circuiting of conductors 239 and 241 by conductor 363. These conductors may be connected to a plug 237 that,

in turn, connects with the trigger cable 32, containing conv ductors 31 and 35, before discussed. The flash apparatus 17 is thus periodically and automatically flashed to expose each successive new position of the film 295 after the film has been moved to such new position. The apparatus, furthern1ore, is quiet at the time that a flash is produced, the motor 217 having stopped, and any life being photographed will not be aware of either noise or the almost instantaneous fiash or light. No gears, claw mechanisms or cams and the like are necessary, furthermore, all of the film-advancement and trigger-initiation being achieved by the cam operation. The assembly of the camera parts along the axis of the housing Zlil provides similar advantages to those discussed in connection with the flash-apparatus housing 17. Should it be desired to operate the armature 249 of the time-delay device 243,

not in response to the spring 265, but under the exclusive control of voltages in the relay Z45, voltage pulses of the desired time duration may be applied to the terminal 267. These terminals 267, for example, may be connected in the before-described photocell circuit, as across the resistor 149 of Fig. 4, so that the triggering may be achieved by self-luminous objects or other radiation. The relay coil 24-5 may also be energized by other external sources of voltage pulses to obtain exposures at the desired successiye intervals of time. r

The apparatus 17201 may be lowered into the water in one position, say upon its side, as with the aid of a side-operated cable, not shown, so that the mercury switches 127 and 75 are in their inoperative positions. By releasing the side-operated cable, not shown, the apparatus 11-201 may be suspended in the position illustrated in Fig. 7 in which the switches 127 and 75 are in their operative positions, thus enabling the apparatus to operate thereafter automatically, periodically flash-photographing whatever may be in front of the camera. If desired, the apparatus 17-291 may be rotated from a vessel in order to obtain a panoramic view of photographic explorations. The photographic camera, moreover, in all embodiments of the invention may, if desired, be replaced by a television camera or any other light-sensitive device.

Further modifications will occur to those skilled in the art and all such are considered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. Apparatus of the character described comprising a housing containing an electric flash-producing circuit, position-controlled switching means adapted to open or close depending upon the position of the housing, and

means for interposing the switching means in the circuit in order, depending upon the position of the housing, either to complete the electrical connections of the circuit through the closed switching means, thereby to render the circuit effective for the production of an electric flash, or to maintain the circuit incomplete at the open switching means, thereby to render the circuit ineffective to produce an electric flash.

2. Apparatus of the character described comprising a housing containing an electric flash-producing system having a flashtuhe, an electric circuit for energizing the flashtube and a trigger circuit forinitiating the energization of the flash-tube by the electric circuit; position-controlled switching means adapted to open or close depending upon the position of the housing; and means for interposing the switching means in the electric circuit and in the trigger circuit in order, depending upon the position of the housing, either to complete the electrical connections of the electric and trigger circuits through the closed switching means, thereby to render the system effective for the production of an electric flash upon the operation of the trigger circuit, or to maintain the electric and trigger circuits incomplete at the open switching means, thereby to render the system ineffective to produce an electric flash.

3. Apparatus of the character described comprising a housing containing an electric flash-producing system having a flashtube, condenser means connected to the flashtube, an electric circuit containing a source of energy for charging the condenser means and a trigger device for initiating the discharge of the condenser means through the flash-tube to produce an electric flash; positioncontrolled switching means adapted to open or close depending upon the position of the housing; and means for interposing the switching means in the electric circuit in order, depending upon the position of the housing, either to complete the electrical connections of the electric circuit through the closed switching means, thereby to charge the condenser means and to render the system effective for the production of an electric flash upon the operation of the trigger device, or to maintain the electric circuit incomplete at the open switching means, thereby to maintain the condenser means uncharged and to render the system ineflective to produce an electric flash.

4. Apparatus of the character described comprising a cylindrical fluid-tight housing containing an electric flashproducing system having a flash-tube mounted at one end, a plurality of condensers disposed in-line along the axis of the cylindrical housing and connected to the flash-tube,

10 an electric circuit containing batteries disposed in-line with the condensers in the housing for charging the condensers, a normally ineffective trigger circuit for initiating, when effective, the energization of the flash-tube by the electric circuit, and a low-impedance switch external to the housing connected to the trigger circuit for rendering the same effective, thereby to initiate the production of an electric flash in the flash-tube; position-controlled switching means adapted to open or close depending upon the position of the housing; and means for interposing the switching means in the electric and trigger circuits in order, depending upon the position of the housing, either to complete the electrical connections of the electric and trigger circuits through the closed switching means, thereby to charge the condensers and to render the system effective for the production of an electric flash upon the rendering effective of the trigger device, or to maintain the electric circuit incomplete at the open switching means, thereby to maintain the condensers uncharged and to render the system inefiective to produce an electric flash.

5. Apparatus of the character described comprising a housing containing an electric flash-producing system having a flash-tube, first condenser means connected to the flash-tube, a first electric circuit containing a source of energy for charging the first condenser means, a. normally ineffective trigger discharge device, second condenser means connected to the trigger discharge device, a second electric circuit for charging the second and means for rendering the trigger discharge device effective to discharge the charged second condenser means therethrough, thereby to initiate the discharge of the first condenser means through the flash-tube to produce an electric flash; a pair of position-controlled switches adapted to open or close depending upon the position of the housing; and means for interposing one of the pair of switches in each of the first and second electric circuits in order, depending upon the position of the housing, either to complete the electrical connections of the electric circuits through the closed switches, thereby to render the system effective for the production of an electric flash, or to maintain the electric circuits incomplete at the open switches, thereby to render the system ineffective to produce an electric flash.

6. Apparatus of the character described comprising a housing containing an electric flash-producing system having a flash-tube, first condenser means connected to the flash-tube, a first electric circuit containing a source of energy for charging the first condenser means, a normally ineffective trigger discharge device, second condenser means connected to the trigger discharge device, a second electric circuit for charging the second condenser means, and means comprising a low-impedance switch external to the housing for rendering the trigger discharge device effective to discharge the charged second condenser means therethrough, thereby to initiate the discharge of the first condenser means through the flash-tube to produce an electric flash; a pair of position-controlled switches adapted to open or close depending upon the position of the housing; and means for interposing one of the pair of switches in each of the first and second electric circuits in order, depending upon the position of the housing, either to complete the electrical connections of the electric circuits through the closed switches, thereby to render the system eifective for the production of an electric flash, or to maintain the electric circuits incomplete at the open switches, thereby to render the system ineffective to produce an electric flash.

7. Apparatus of the character described comprising a housing containing an electric flash-producing system having a flash-tube, first condenser means connected to the flash-tube, a first electric circuit containing a source of energy for charging the first condenser means, a normally ineffective trigger discharge device, second condenser means connected to the trigger discharge device,

condenser means,

through the flash-tube to produce-an electric fiash; a pair of position-controlled switches adapted to open or close depending upon the position of the housing; and means for interposing one of the pair of switches in each of the first and second electric circuits in order, depending upon the position of the housing, either to complete the electrical connections of the electric circuits through the closed switches, thereby to render the system effective for the production of an electric flash, or to maintain the electric circuits incomplete at the open switches, there by to render the system ineffective to produce an electric flash.

8. Apparatus of the character described comprising a housing containing an electric flash-producing system having a gaseousdischarge flash-tube provided with an anode, a cathode and a trigger electrode, condenser means connected between the anode and the cathode, an electric circuit containing a source of energy for charging the condenser means, a trigger device including a trigger transformer provided with a secondary Winding connected to the trigger electrode and a. spark gap connected across the secondary winding for initiating the discharge of the condenser means through the flash-tube to produce an electric flash; position-controlled switching means adapted to open or close depending upon the position of the housing; and means for interposing the switching means in the electric circuit in order, depending upon the position of the housing, either to complete the electrical connections of the electric circuit through the closed switching means, thereby to charge the condenser means and to render the system effective for the production of an electric flash upon the operation of the trigger device, or to maintain the electric circuit incomplete at the open switching means, thereby to maintain the condenser means un- 12 charged and to render the system inefifective to produce an electric flash.

9. Apparatus of the'characteir described comprising a gaseous-discharge flash-tube provided with an anode, a cathode and a trigger electrode, condenser means connected between the anode and the cathode, an electric circuit containing a source of energy for charging the condenser means, a trigger device including a trigger transformer provided with a secondary winding connected to the trigger electrode and means for energizing the trigger transformer to initiate the discharge of the condenser means through the flash-tube to produce an electric flash, and a spark gap connected with the secondary winding of the trigger transformer for increasing the effective resonant frequency ofthe said connection from the secondary winding to the trigger electrode, thereby further to assist in the initiation or" the said discharge.

References Cited in the file of this patent UNITED STATES PATENTS 2,073,247 Miller Mar. 9, 1937 2,099,483 Hinde Nov. 16, 1937 2,170,584 Ayers Aug. 22, 1939 2,358,796 Edgerton Sept. 26, 1944 2,449,799 Alvarez et al. J. Sept. 21, 1948 2,478,907 Edgerton Aug. 16, 1949 2,485,037 Clark s Get. 18, 1949 2,492,247 Weaving et al Dec. 27, 1949 2,509,005 Lord May 23, 1950 2,550,698 King et al. May 1, 1951 2,624,831 Far'oer Ian. 6, 1953 2,697,392 Zimberotf et al. Dec. 21, 1954 2,754,721 Grass July 27, 1956 2,760,417 Laval Aug. 23, 1956 OTHER REFERENCES New Apparatus and Materials, The British Journal of Photography, vol. 101, No. 4907, page 286 (June 4, 1954). s 

